﻿using System;
using System.Security.Cryptography;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Collections.Specialized;
using System.Net;
using System.Globalization;
using System.IO;

using Mr.HttpBodyWrapper;

namespace OAuth
{
    public class OAuthUtility
    {
        /// <summary>
        /// Comparer class used to perform the sorting of the query parameters
        /// </summary>
        protected class QueryParameterComparer : IComparer<OAuthQueryParameter>
        {
            #region IComparer<QueryParameter> Members

            public int Compare(OAuthQueryParameter x, OAuthQueryParameter y)
            {
                if (x.Name == y.Name)
                {
                    return string.Compare(x.Value, y.Value);
                }
                else
                {
                    return string.Compare(x.Name, y.Name);
                }
            }

            #endregion
        }

        public static readonly string OAuthVersion = "1.0";
        public static readonly string OAuthParameterPrefix = "oauth_";

        //
        // List of know and used oauth parameters' names
        //        
        public static readonly string OAuthConsumerKeyKey = "oauth_consumer_key";
        public static readonly string OAuthCallbackKey = "oauth_callback";
        public static readonly string OAuthVerifierKey = "oauth_verifier";
        public static readonly string OAuthVersionKey = "oauth_version";
        public static readonly string OAuthSignatureMethodKey = "oauth_signature_method";
        public static readonly string OAuthSignatureKey = "oauth_signature";
        public static readonly string OAuthTimestampKey = "oauth_timestamp";
        public static readonly string OAuthNonceKey = "oauth_nonce";
        public static readonly string OAuthTokenKey = "oauth_token";
        public static readonly string OAuthTokenSecretKey = "oauth_token_secret";

        public static readonly string HMACSHA1SignatureType = "HMAC-SHA1";
        public static readonly string PlainTextSignatureType = "PLAINTEXT";
        public static readonly string RSASHA1SignatureType = "RSA-SHA1";

        protected Random random = new Random();

        protected string unreservedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~";

        public static readonly OAuthUtility Instance = new OAuthUtility();
        /// <summary>
        /// constructor for private because of instance
        /// </summary>
        private OAuthUtility() { }

        /// <summary>
        /// Helper function to compute a hash value
        /// </summary>
        /// <param name="hashAlgorithm">The hashing algoirhtm used. If that algorithm needs some initialization, like HMAC and its derivatives, they should be initialized prior to passing it to this function</param>
        /// <param name="data">The data to hash</param>
        /// <returns>a Base64 string of the hash value</returns>
        private string ComputeHash(HashAlgorithm hashAlgorithm, string data)
        {
            if (hashAlgorithm == null)
            {
                throw new ArgumentNullException("hashAlgorithm");
            }

            if (string.IsNullOrEmpty(data))
            {
                throw new ArgumentNullException("data");
            }

            byte[] dataBuffer = System.Text.Encoding.ASCII.GetBytes(data);
            byte[] hashBytes = hashAlgorithm.ComputeHash(dataBuffer);

            return Convert.ToBase64String(hashBytes);
        }

        /// <summary>
        /// Internal function to cut out all non oauth query string parameters (all parameters not begining with "oauth_")
        /// </summary>
        /// <param name="parameters">The query string part of the Url</param>
        /// <returns>A list of QueryParameter each containing the parameter name and value</returns>
        private List<OAuthQueryParameter> GetQueryParameters(string parameters)
        {
            if (parameters.StartsWith("?"))
            {
                parameters = parameters.Remove(0, 1);
            }

            List<OAuthQueryParameter> result = new List<OAuthQueryParameter>();

            if (!string.IsNullOrEmpty(parameters))
            {
                string[] p = parameters.Split('&');
                foreach (string s in p)
                {
                    if (!string.IsNullOrEmpty(s) && !s.StartsWith(OAuthParameterPrefix))
                    {
                        if (s.IndexOf('=') > -1)
                        {
                            string[] temp = s.Split('=');
                            result.Add(new OAuthQueryParameter(temp[0], temp[1]));
                        }
                        else
                        {
                            result.Add(new OAuthQueryParameter(s, string.Empty));
                        }
                    }
                }
            }

            return result;
        }

        /// <summary>
        /// This is a different Url Encode implementation since the default .NET one outputs the percent encoding in lower case.
        /// While this is not a problem with the percent encoding spec, it is used in upper case throughout OAuth
        /// </summary>
        /// <param name="value">The value to Url encode</param>
        /// <returns>Returns a Url encoded string</returns>
        public string UrlEncode(string value)
        {
            StringBuilder result = new StringBuilder();

            foreach (char symbol in value)
            {
                if (unreservedChars.IndexOf(symbol) != -1)
                {
                    result.Append(symbol);
                }
                else
                {
                    byte[] temp = Encoding.UTF8.GetBytes(symbol.ToString());
                    foreach (byte tem in temp)
                    {
                        result.Append('%' + Convert.ToString(tem, 16).ToUpper());
                    }
                }
            }
            return result.ToString();
        }

        public string UrlDecode(string value)
        {
            return HttpUtility.UrlDecode(value);
        }

        /// <summary>
        /// Normalizes the request parameters according to the spec
        /// </summary>
        /// <param name="parameters">The list of parameters already sorted</param>
        /// <returns>a string representing the normalized parameters</returns>
        public string NormalizeRequestParameters(IList<OAuthQueryParameter> parameters)
        {
            StringBuilder sb = new StringBuilder();
            OAuthQueryParameter p = null;
            for (int i = 0; i < parameters.Count; i++)
            {
                p = parameters[i];
                sb.AppendFormat("{0}={1}", p.Name, p.Value);

                if (i < parameters.Count - 1)
                {
                    sb.Append("&");
                }
            }

            return sb.ToString();
        }

        /// <summary>
        /// Generate the signature base that is used to produce the signature
        /// </summary>
        /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
        /// <param name="consumerKey">The consumer key</param>        
        /// <param name="token">The token, if available. If not available pass null or an empty string</param>
        /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
        /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
        /// <param name="signatureType">The signature type. To use the default values use <see cref="OAuthBase.SignatureTypes">OAuthBase.SignatureTypes</see>.</param>
        /// <returns>The signature base</returns>

        /// <summary>
        /// Generate the signature base that is used to produce the signature
        /// </summary>
        /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
        /// <param name="consumerKey">The consumer key</param>        
        /// <param name="token">The token, if available. If not available pass null or an empty string</param>
        /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
        /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
        /// <param name="signatureType">The signature type. To use the default values use <see cref="OAuthBase.SignatureTypes">OAuthBase.SignatureTypes</see>.</param>
        /// <param name="callback">the callback url, if available. if not available pass null or an empty string</param>
        /// <param name="scope">the callback url, if available. if not available pass null or an empty string</param>
        /// <param name="normalizedUrl"></param>
        /// <param name="normalizedRequestParameters"></param>
        /// <returns>signature</returns>
        public string GenerateSignatureBase(
            Uri url,
            string consumerKey,
            string token,
            string tokenSecret,
            string verifier,
            string httpMethod,
            string timeStamp,
            string nonce,
            string callback,
            string signatureType,
            out string normalizedUrl,
            out string normalizedRequestParameters,
            params OAuthQueryParameter[] queryParameters)
        {
            if (token == null)
            {
                token = string.Empty;
            }

            if (tokenSecret == null)
            {
                tokenSecret = string.Empty;
            }

            if (verifier == null)
            {
                verifier = string.Empty;
            }

            if (string.IsNullOrEmpty(consumerKey))
            {
                throw new ArgumentNullException("consumerKey");
            }

            if (string.IsNullOrEmpty(httpMethod))
            {
                throw new ArgumentNullException("httpMethod");
            }

            if (string.IsNullOrEmpty(signatureType))
            {
                throw new ArgumentNullException("signatureType");
            }

            normalizedUrl = null;
            normalizedRequestParameters = null;

            List<OAuthQueryParameter> parameters = GetQueryParameters(url.Query);
            parameters.Add(new OAuthQueryParameter(OAuthVersionKey, OAuthVersion));
            parameters.Add(new OAuthQueryParameter(OAuthNonceKey, nonce));
            parameters.Add(new OAuthQueryParameter(OAuthTimestampKey, timeStamp));
            parameters.Add(new OAuthQueryParameter(OAuthSignatureMethodKey, signatureType));
            parameters.Add(new OAuthQueryParameter(OAuthConsumerKeyKey, consumerKey));


            if (queryParameters != null && queryParameters.Length > 0)
            {
                foreach (OAuthQueryParameter query in queryParameters)
                {
                    parameters.Add(query);
                }
            }
            // Do not need the callback in the signature while getting the access token.
            if (!string.IsNullOrEmpty(callback))
            {
                parameters.Add(new OAuthQueryParameter(OAuthCallbackKey, callback));
            }

            if (!string.IsNullOrEmpty(token))
            {
                parameters.Add(new OAuthQueryParameter(OAuthTokenKey, token));
            }

            if (!string.IsNullOrEmpty(verifier))
            {
                parameters.Add(new OAuthQueryParameter(OAuthVerifierKey, verifier));
            }

            parameters.Sort(new QueryParameterComparer());

            normalizedUrl = string.Format("{0}://{1}", url.Scheme, url.Host);
            if (!((url.Scheme == "http" && url.Port == 80) || (url.Scheme == "https" && url.Port == 443)))
            {
                normalizedUrl += ":" + url.Port;
            }
            normalizedUrl += url.AbsolutePath;
            normalizedRequestParameters = NormalizeRequestParameters(parameters);

            StringBuilder signatureBase = new StringBuilder();
            signatureBase.AppendFormat("{0}&", httpMethod.ToUpper());
            signatureBase.AppendFormat("{0}&", UrlEncode(normalizedUrl));
            signatureBase.AppendFormat("{0}", UrlEncode(normalizedRequestParameters));

            return signatureBase.ToString();
        }

        /// <summary>
        /// Generate the signature value based on the given signature base and hash algorithm
        /// </summary>
        /// <param name="signatureBase">The signature based as produced by the GenerateSignatureBase method or by any other means</param>
        /// <param name="hash">The hash algorithm used to perform the hashing. If the hashing algorithm requires initialization or a key it should be set prior to calling this method</param>
        /// <returns>A base64 string of the hash value</returns>
        public string GenerateSignatureUsingHash(string signatureBase, HashAlgorithm hash)
        {
            return ComputeHash(hash, signatureBase);
        }


        public string GenerateSignature(
            Uri url,
            string consumerKey,
            string consumerSecret,
            string token,
            string tokenSecret,
            string verifier,
            string httpMethod,
            string timeStamp,
            string nonce,
            string callback,
            SignatureTypes signatureType,
            params OAuthQueryParameter[] queryParameters)
        {
            string normalizedUrl = string.Empty, normalizedRequestParameters = string.Empty;
            return GenerateSignature(
                url,
                consumerKey,
                consumerSecret,
                token,
                tokenSecret,
                verifier,
                httpMethod,
                timeStamp,
                nonce,
                callback,
                signatureType,
                out normalizedUrl,
                out normalizedRequestParameters,
                queryParameters);
        }

        /// <summary>
        /// Generates a signature using the HMAC-SHA1 algorithm
        /// </summary>		
        /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
        /// <param name="consumerKey">The consumer key</param>
        /// <param name="consumerSecret">The consumer seceret</param>
        /// <param name="token">The token, if available. If not available pass null or an empty string</param>
        /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
        /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
        /// <returns>A base64 string of the hash value</returns>
        public string GenerateSignature(
            Uri url,
            string consumerKey,
            string consumerSecret,
            string token,
            string tokenSecret,
            string verifier,
            string httpMethod,
            string timeStamp,
            string nonce,
            string callback,
            out string normalizedUrl,
            out string normalizedRequestParameters,
            params OAuthQueryParameter[] queryParameters)
        {
            return GenerateSignature(
                url,
                consumerKey,
                consumerSecret,
                token,
                tokenSecret,
                verifier,
                httpMethod,
                timeStamp,
                nonce,
                callback,
                SignatureTypes.HMACSHA1,
                out normalizedUrl,
                out normalizedRequestParameters,
                queryParameters);
        }

        /// <summary>
        /// Generates a signature using the specified signatureType 
        /// </summary>		
        /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
        /// <param name="consumerKey">The consumer key</param>
        /// <param name="consumerSecret">The consumer seceret</param>
        /// <param name="token">The token, if available. If not available pass null or an empty string</param>
        /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
        /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
        /// <param name="signatureType">The type of signature to use</param>
        /// <returns>A base64 string of the hash value</returns>
        public string GenerateSignature(
            Uri url,
            string consumerKey,
            string consumerSecret,
            string token,
            string tokenSecret,
            string verifier,
            string httpMethod,
            string timeStamp,
            string nonce,
            string callback,
            SignatureTypes signatureType,
            out string normalizedUrl,
            out string normalizedRequestParameters,
            params OAuthQueryParameter[] queryParameters)
        {
            normalizedUrl = null;
            normalizedRequestParameters = null;

            switch (signatureType)
            {
                case SignatureTypes.PLAINTEXT:
                    return HttpUtility.UrlEncode(string.Format("{0}&{1}", consumerSecret, tokenSecret));
                case SignatureTypes.HMACSHA1:
                    string signatureBase =
                        GenerateSignatureBase(
                            url,
                            consumerKey,
                            token,
                            tokenSecret,
                            verifier,
                            httpMethod,
                            timeStamp,
                            nonce,
                            callback,
                            HMACSHA1SignatureType,
                            out normalizedUrl,
                            out normalizedRequestParameters,
                            queryParameters);
                    HMACSHA1 hmacsha1 = new HMACSHA1();
                    hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : tokenSecret));

                    return GenerateSignatureUsingHash(signatureBase, hmacsha1);
                case SignatureTypes.RSASHA1:
                    throw new NotImplementedException();
                default:
                    throw new ArgumentException("Unknown signature type", "signatureType");
            }
        }

        /// <summary>
        /// Generate the timestamp for the signature        
        /// </summary>
        /// <returns></returns>
        public virtual string GenerateTimeStamp()
        {
            // Default implementation of UNIX time of the current UTC time
            TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
            return Convert.ToInt64(ts.TotalSeconds).ToString();
        }

        /// <summary>
        /// Generate a nonce
        /// </summary>
        /// <returns></returns>
        public virtual string GenerateNonce()
        {
            string nonce = random.Next(123400, 9999999).ToString();
            return nonce;
        }
    }

    /// <summary>
    /// Provides a predefined set of algorithms that are supported officially by the protocol
    /// </summary>
    public enum SignatureTypes
    {
        HMACSHA1,
        PLAINTEXT,
        RSASHA1
    }
}
